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Viscous drop in compressional Stokes flow

Published online by Cambridge University Press:  27 February 2013

Michael Zabarankin*
Affiliation:
Department of Mathematical Sciences, Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030, USA
Irina Smagin
Affiliation:
The Wolfson Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
Olga M. Lavrenteva
Affiliation:
The Wolfson Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
Avinoam Nir
Affiliation:
The Wolfson Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
*
Email address for correspondence: [email protected]

Abstract

The dynamics of the deformation of a drop in axisymmetric compressional viscous flow is addressed through analytical and numerical analyses for a variety of capillary numbers, $\mathit{Ca}$, and viscosity ratios, $\lambda $. For low $Ca$, the drop is approximated by an oblate spheroid, and an analytical solution is obtained in terms of spheroidal harmonics; whereas, for the case of equal viscosities ($\lambda = 1$), the velocity field within and outside a drop of a given shape admits an integral representation, and steady shapes are found in the form of Chebyshev series. For arbitrary $Ca$ and $\lambda $, exact steady shapes are evaluated numerically via an integral equation. The critical $\mathit{Ca}$, below which a steady drop shape exists, is established for various $\lambda $. Remarkably, in contrast to the extensional flow case, critical steady shapes, being flat discs with rounded rims, have similar degrees of deformation ($D\sim 0. 75$) for all $\lambda $ studied. It is also shown that for almost the entire range of $\mathit{Ca}$ and $\lambda $, the steady shapes have accurate two-parameter approximations. The validity and implications of spheroidal and two-parameter shape approximations are examined in comparison to the exact steady shapes.

Type
Papers
Copyright
©2013 Cambridge University Press

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